SBS: Firewall error using internet config wizard

I have a SBServer set up behind a WRT54G Router.
The sbserver handles the DHCP.
Workstations use wireless to connect to network.

Problem now is that my mobile devices such as laptops and iphone's cant contact the exchange server. (As a note, locally the exchange works)
So I figured its a firewall issue, the ports to the exchange server isnt opened.
I've ran the 'Connect to the Internet' wizard (a few times) to try solve the problem, but no matter the options I choose, I will get an error at Firewall Configuration
  "An error occured while configuring a componet" (continute/abort etc)

If I check the Firewall settings for my network adapter on the SBServer (cable to the router) I get error:
  "Windows Firewall cannot run because another program or service is running that might use the network address translation component (Ipnet.sys)."

Granted, the exchange ports isnt forwarded to the SBServer. Actually, no ports are open, and thus it raises another odd problem; even though port 80 isnt forwared to the SBServer, I can access the webserver from the internet (albeit Im restricted access even though I select to allow in the wizard), but anyhow, I can communicate with the server, when I shouldnt?

I'm thoroughly perplexed. :P
(Hope I could formulate my problem clearly enough)